1. Field of the Invention
The present invention relates to LED control circuits, and particularly to an LED control circuit capable of automatically controlling brightness of LEDs according to ambient light conditions.
2. Description of Related Art
Light-emitting diode (LED) arrays have shown great potential as a light source in LCD backlighting systems. When compared to other light sources such as cold cathode fluorescent lamp (CCFL) sources, LED arrays are desirable for their low-temperature performance, ease of heat-sinking, dimming range, small size, low power consumption, relatively low cost, luminous efficacy, and directional emission.
Some LCD backlights are required to emit light of a constant brightness during use. Other LCD backlights are required to perform in multiple viewing modes, each of the modes having different brightness requirements. For example, an LCD display may be required to perform in a daylight viewing mode as well as in a night-time viewing mode, and the brightness requirements for the viewing modes are vastly different from each other. In such circumstances, it would be helpful to control the luminance of the backlight.
What is needed, therefore, is an LED control circuit which can solve above problem.